Underground storage system



June 25, 1957 1 P. MEADE ETAI- UNDERGROUND STORAGE SYSTEM Filed May 22,1953 2 Sheets-Sheet l .n L. PMM@ @d BY 6J. Dommxpd? Hwaw *M ATTORNEYSJune 25 11957 L p, MEADE ETAL. 2,796,739

UNDERGROUND STORAGE SYSTEM Filed May 22, 1953 2 Sheets-Sheet 2 ATTOR/VEY' nited States UNBERGRUND STORAGE SYSTEM Application May 22,1953, Serial No. 356,798

20 Claims. (Cl. 62-1) This invention relates to underground storagesystems. In a further aspect this invention relates to a novel methodfor sealing underground storage systems for fluids. In a still furtheraspect this invention relates to underground storage systems for thestorage of liqueed petroleum gas.

Constantly expanding production of uids for the industries of thiscountry and elsewhere has created a definite problem in providingsuitable storage facilities for these fluids. In the petroleumindustries in particular the problem of storage of liquefied petroleumgas is presently an urgent one due to the cost of storage in surfaceequipment, such as steel tanks, and due to the massive constructionrequired to withstand the vapor pressure of such liquids. Also adding tothis problem of adequate storage facilities is the fact that manyindustries experience seasonal peak loads in the requirements for theirfluid products and corresponding seasonal slack periods. Thesefluctuations in requirements require large storage facilities and theadvantages of underground storage -of fluids have lately come to theattention of the industry.

The known methods of underground storage of fluids comprise storage inimpermeable caverns, either naturally formed or mined out of impermeablerock, such as shales and limestone. Naturally occurring formations suchas these are difficult to find and present problems in perfecting aclosed container to hold the fluids to be stored. Often expensivelinings are required to make suchl natural or mined caverns impermeable.

Underground storage systems have been developed in salt formations butthe disadvantage of these systems lies in part in the fact that thereare practical limitations to the maximum size of such undergroundstorage Caverns. As a result, the most difficult problems in thedevelopment of underground storage systems to date usually are theselection of a suitable site and the attainment of a sealed container.

In accordance with this invention, an underground storage system isprovided which is adaptable to a wide range of sites and therebydiminishes the problem of finding an advantageous location for theunderground storage system. Furthermore, a method for sealing thecontainers of an underground storage system is provided which iseconomical and yet is extremely effective to prevent fluid lossestherefrom. We have discovered that an undergroundY storage cavernlocated in a permeable, water-bearing formation in which the water inthe cavern walls is frozen to render said walls impermeable to the uidsstored, furnishes a reliable, economical and trouble-free undergroundstorage system. In accordance with a preferred embodiment of ourinvention the refrigeration required yto freeze the water in the cavernwalls is provided in the uid stored by withdrawing the vapors of thestored fluid, compressing, condensing and returning these condensedvapors to the underground storage cavern. Additionally, the system isprovided with automatic controls which continuously pump 17 from the icein well 5 to therposition shown f 2,796,739 Patented June 25, 1957,

monitor the temperature of the frozen cavern walls and the vaporpressure of the fluids stored and start the withdrawal of the vapors ofthe stored liquid as required to maintain said walls in a frozen andtherefore imf permeable condition.

It is an object of this invention to provide a novel and improvedunderground storage system.

It is a further object to provide an underground storage system for uidswhere the diculty of selection of a. site is minimized.

It is a Vfurther object to provide a novel method for sealing thecontainers of an underground storage sysf tem for uids.

Various other objects, advantages and features of this invention willbecome apparent from the following d e.- tailed description taken inconjunction with the accompanying drawings in which:

Figure lY is a vertical sectional view, partly in elevaf tion, of theunderground storage system of this invention; and

Figure 2 is a diagrammatic representation in further detail of thecomponent parts of the automatic control assembly.

Referring no w to Figure 1 of the drawings, reference numeral 1identities the surface of the earth under which our storage Caverns arelocated. It is to be understood that our disclosure encompasses aplurality of Caverns as well as a single underground storage cavern suchas 1s illustrated in Figure 1. The earth in which our under: groundstorage cavern is located should b e a waterf bearing formation andpermeable, and generally it is preferred that the cavern be locatedbelow the minimum water table in such a formation. A shaft 3 extendsfrom the surface of the earth downward to a position adjacent to cavern2, and below, to form a recess orwell 5.-' Tunnels 7 and 9 connect shaft3 to the storage cavern 2. The lower tunnel 7 connects the lower regionof cavern 2 to shaft 3 and tunnel 9 connects the upper region of cavern2 to shaft 3. The shaft 3 is provided with a metal liner 13 which isembedded in cement 11 in the earth surrounding shaft 3 and a metal linerhead 15 is attached to liner 13, as shown to seal the contents of theunderground storage system.

A pipe 14 and valve 16 connected thereto are provided in the liner head15 to permit purging of the storage system of air when the uids to bestored are rst introduced. A i

A motor and pump combination 17 as disclosed in lthe copendingapplication of L. P. Meade, Serial No.

314,541, tiled on October 13, 1952, now abandoned, is provided andplaced as shown in Figure l by the dotted lines in the well or recess 5to remove water from' the system during excavation operations throughthe withdrawal pipe 19 connected thereto. Attached to liner head 15 is astripper-type tubing head 20, such as those used in the petroleumindustry,lwhich provides means for supporting withdrawal pipe 19 as wellas preventing loss of stored fluids when withdrawal pipe V19 is raised.The motor and pump combination 17 Vis provided with a heating element 18to allow the raising of motor and by solid lines when the storage systembecomes frozen. When the cavern has been frozen the motor andpump V17are raised above the level of ice 22 in the bottom of cavern 2 and areused for withdrawing product from the underground storage system. AVtill pipe 21 is provided for introducing iluids to be stored into theunderground storage systemv and it is to be noted Athat Yfansubstantiallength of fill pipe 21 is positioned belowthe level of the ice 2.2 inthe bottom ofthe cave-m12 wit-h the outlet of lill pipe 21 protrudingabove the level of said ice 22 and in heat exchange relationshipthereto, which provides a source of stored refrigeration for theincorning uids to the storage system.

A vapor withdrawal pipe 23 is Yprovided to withdraw the vapors of theVfluids stored in the system, thereby decreasing the pressure in theunderground storage cavern and producing a cooling effect which causesthe water in the cavern walls to become frozen. The vapors are withdrawnthrough pipe 23 by the Vmotor and compressor combination 25 and passedthrough pipe 27 to condenser 29. The condensed and compressed vapors aredrawn through pipe 31 by pump 30 and passed via fill pipe 21 back to theundergroundy storage system. A check valve 32 is provided in fil-l pipe21 to prevent the compressed and condensed vapors from being pumped outof the system through pipe 21.

Y A liquid level assembly 33 is provided so that the level of liquids inthe cavern can be readily determined at all times. Also, when thestorage system has been frozen,

the floatV indicates the level of ice 22 in the bottom of the system,`as well. The details of tliquid level indicator assembly 33 aredisclosed in the copending application of L. P. Meade, Serial No.314,541, le'd October 13, 1952, now abandoned. Liquid level indicatorassembly 33 includes a perforated well or tube 35 which extendsdownwardly to the lowest regions of shaft 3. Movable vertically in tube35 is a oat 37 secured to a tape 38 which extends upwardly through thetube 35 to the liquid level indicator assembly 33.

An automatic control assembly is connected to motor and compressorcombination 25 by wires 26 and is provided to initiate the withdrawal ofthe vapors of the stored fluids as required to cool the contents of thecavern and thereby maintain the water in the earth surrounding saidcavern in a frozen condition. Lead Vwires 41 extend from the automaticcontrol assembly 39 into cavern 2 and are attached to temperaturevresponsive switches 43, 45, 47, 49, 51, 53, and 57. 'Ihese temperatureresponsive 'switches are connected to lead wires 41 and are placed inthe walls of the cavern and arerresponsive to temperature changestherein in a manner that the electrical circuit in lead wires 41 isclosed when the temperature surrounding said temperature responsiveswitches rises to a rst preselected temperature. Such a'rst p-reselectedtemperature is approximately the freezing point of the water in theparticular earth and water formation surrounding storage cavern 2 andmay be easily ascertained 'during the construction of the cavern. Inaddition to thetemperature responsive switches the automatic controlassembly 39 includes a pressure controller switch 59 which is connectedthrough the liner head 15 to shaft 3 by pipev 61. The pressurecontroller switch 59 also is connected to lead .wires 41 and will closethe circuit in said lead wires when the pressure within the shaft 3exceeds a tirstrpreselected pressure in'controller switch S9. Such apreselected pressure is approximately the vapor pressure of the iluidstored at approximately the temperature at which the water in the earthsurrounidinng the cavern freezes.

In the situation where the underground storage system comprises aplurality of Caverns, tunnels 7a and 9a, ller pipe 21aand lead wires 41arepresent features corresponding thereto in the single cavern shown.

l YReferring now Vto Figure 2 of the drawings, the automatic controlassembly is illustrated further.

AB-phase current source 42 is connected tothe motor and compressorcombination 25 by wires 26 througha relay or contactor switch 40 havingcontacts` 44 to disengage current sourcev42 from motor and compressorcombination 25.` The contacts 44 are closed upon energization of asolenoid coil 46 by a current source 48.

nected in a parallel circuit with solenoid coil 46. Pressure responsiveswitch 59 is connected through liner head 15 to shaft 3 by pipe 61 andthereby is responsive to the pressure of the vapors of the fluid storedin the cavern. Pressure responsive switch 59 remains open until thepressure of said vapors reaches a first preselected value which ispreferably approximately the vapor pressure of the uid stored which isexhibited at approximately the temperature at which the water in theearth surrounding the cavern freezes. When the vapor pressure of the uidstored exceeds this last described pressure, pressure responsive switch59 closes and the motor and compressor combination 25 is therebystarted. Temperature responsive switches 43, 45, etc., operate in ananalogous manner, closing the circuit in the relay and thereby startingmotor and compressor combination 25 when the temperature of the waterand earth surrounding the cavern exceeds a irst preselected value, whichis preferably approximately the freezing point of water in the earthsurrounding the cavern. When one any one of the pressure responsiveswitch and temperature responsive switches closes, the motor andcompressor combination 25 is actuated to draw ot vapors of the storedfluid and thereby cool the cavern. Our invention is applicable to thestorage of any uid whose freezing point is below the freezing point ofthe water in the earth wherein the storage cavern is located.

The system herein disclosed, whereby refrigeration is provided by thefluid stored, is applicable to any ilui'd which is stored in the liquidIstate. Liqueed petroleum gas and liqueiied ammonia are illustrative oflluids which are applicable to the underground storage system of ourinvention. However, the novel system herein disclosed for storing fluidsin an underground storage system is broadly applicable to fluids whetheror not in a liquid state. Where liquids are stored which boil above thefreezing point of the water in the cavern walls at atmos-l phericconditions it is advantageous to admix `with such liquids more volatilecomponents in concentrations which will not disturb the specificationsfor such stored liquids Means to actuate sai'd'relay are provided which`comprise f and yet will allow the withdrawal of such volatilecomponents by the motor 'and compressor combination 2S and thereby makesuch heavier liquids applicable to a self refrigeration process.

1 There are two conditions which arise in the construction and rstoperation of our storage system. One concerns the condition when thevolume of water in the earth and water formation isV not so great thatearth formation is unconsolidated, and in this case the waterencountered is pumped out continuously while the cavern is beingexcavated. However if the amount of water is excessive to the extentthat the earth and water formation is unconsolidated, the water in theentire mass of earth where the cavern is to be located must be frozenbefore excavation is begun and maintained frozen throughout theconstruction of the underground storage system and first filling. Asuitable refrigerating medium, e. g., brine, is circulated throughydrilled holes in the earth formation to freeze the water in the earthAand thereby allow the excavation operation toY be accomplished.

In the case where the amount of water in the earth is not so large as torequireV freezingbefore excavation is begun, the pump and motor.combination 17 is operated continu-V ously in well 5 to prevent theYaccumulation of water in the cavern. When the excavation work iscomplete and Vthe necessary shaft liner, lling and withdrawal lines andsurface equipment are installed, theiilling operation is started. Sincethe pressureginside the cavern is lower than the pressure in thesurrounding earth and water due to the continuous Withdrawal of water,the uids introduced to the cavern Vwill vaporize immediately and beginto cool the cavern walls.k Air in the system is bled of through Y Y pipe14 and valve 16 to prevent a buildup inl pressure. l

When the cavern is thoroughly purged, valve 16 'is closed and the motorand Ycompressor assembly 25 is started. During the time that the uidsare first being introduced to are thestorge cavern, before the water inthe cavern Walls is frozen, the rstored fluids will not escape throughthe cavern walls because the pressure within the cavern is maintainedlower than the pressure outside the cavern due to the continuouswithdrawal of water by motor and pump 17. After the water in the cavernwalls bceomes frozen as evidenced by the opening of the circuit in leadlines 41 by the temperature responsive switches and the pressureresponsive switch, the motor and pump 17 is heated by heating elements18 to free motor and pump 17 from the ice and raised to a position abovethe ice level 22 in the bottom of the cavern to be used to Withdraw thestored fluidsvas desired from the storage system.

In the case where the amount of water in the earth surrounding thecavern is so great that the entire formation must be frozen beforeexcavation is begun, the entire operation in constructing theundergro-und storage system of our invention is completed While thewater in the earth is maintained in a frozen condition by externalrefrigeration before the fluid to be stored is introduced. Upon theintroduction of the uid to be stored, the starting operation thenbecomes identical with that described above and the externalrefrigeration is discontinued when the rate of vaporization of thestored fluid is sufficient to maintain the vtemperature of theunderground cavern below the freezing point of the water in the earthsurrounding the cavern.

In the case where the entire earthen formation is not frozen by externalrefrigeration during the excavation operation, the pressure within thecavern is controlled, as stated above, by the continuous withdrawal ofwater from the shaft 3 and well 5. Therefore it is not necessary thatthe minimum water table in the site selected for the underground storagesystem of our invention be far above the cavern roof. It is onlypreferred that the earthen formation be saturated with water to adistance far enough above the cavern roof that a substantial layer ofice can be formed in the cavern walls.

It is to be noted that the distance from the surface of the ground tothe top of the cavern can be varied according to the vapor pressure ofthe fluid to be stored therein at or near the freezing point of thewater in the earth surrounding said cavern. A workable rule to follow isthat the cavern be located at a distance below the surface of the earthapproximately equal to one foot for each pound of vapor pressureexhibited by the stored fluid at thefreezing temperature of the water inthe earth surrounding the storage cavern.

While our invention has been described in connection with a presentpreferred embodiment thereof, it is to be understood that thisdescription is illustrative only, and is not intended to limit theinvention.

We claim:

1. A method for sealing an underground cavern for the storage ofliquids, said cavern having been formed in a permeable water-bearingformation underground, which comprises introducing said liquids intosaid cavern, withdrawing the vapors of said liquids to produce a coolingeffect to freeze the water in the earth surrounding said cavern,comprising and condensing said vapors and returning said compressed andcondensed vapors to said cavern.

2. A method for sealing an underground cavern for the storage ofliquefied petroleum gas, said cavern having been formed in a permeable,water-bearing formation underground, which comprises introducing saidliquefied petroleum gas into said cavern, withdrawing the vapors of saidliquefied petroleum gas to produce a cooling effect to freeze the waterin the earth surrounding said cavern, compressing and condensing saidvapors and returning said compressed and condensed vapors to saidcavern.

3. A method for sealing a plurality of underground caverns for thestorage of liquefied petroleum gas, said caverns having been formed in apermeable, water-bearing formationiunderground, which comprisesintroducingsaid liqueedpetroleum gas into `said Caverns, withdrawingthevapors of said liquefied petroleum gas to produce a cooling 6 elect tofreeze the Water in the? earth surroundingsaid Caverns, compressing andcondensing said vaporsfand re-` turning said compressed and condensed'vapors to said caverns.

4. In an underground storage system for liquids, in combination, anunderground storage cavern, the Walls of said cavern being defined byand consisting of the surrounding subsurface media, said media being intheir ordinary condition permeable, water-bearing subsurface strata, ashaft extending from the surface of the earth to a region adjacent tosaid cavern, means for connecting said shaft with said cavern, means forintroducing a liquidY to be stored into said cavern and meansfor coolingsaid cavern by withdrawing vapors of said liquid so as to freeze thewater in the earth surrounding said cavern.

5. In an underground storage .system for liquids, in com-- bination, anunderground storage cavern, a shaft extendf ing from the surface of theearth to a regionv adjacent to said cavern, means for connecting saidshaftY with said cavern, and means for cooling said cavern to freeze`the water in the earth surrounding said cavern which comprises meansfor introducing said liquids into said cavern, and means forwithdrawing, compressing, condensing and returning the vapors of saidliquids to said cavern. Y

6. In an underground storage system for liquids, in combination, anunderground storage cavern, a shaft extending from the surface of theearth to a region adjacent to said cavern, means for connecting saidshaft with said cavern, means for cooling said cavern to freeze thewater in the earth surrounding said cavern comprising means forintroducing said liquids into said cavern, means for withdrawing,compressing, condensing and'returning the vapors of said liquids to saidcavern, and an automatic control assembly means to actuate saidwithdrawal and compressor means, said automatic control assembly meansbeing re.- sponsive to an increase in the temperature above a firstpreselected temperature of the water in the earth surrounding saidcavern.

7. In an underground storage system for liquids, in combination, anunderground storage cavern, a shaft extending from the surface of theearth to a region adjacent to said cavern, means for connecting saidshaft with said cavern, means for cooling said cavern to freeze thewater -in the earth surrounding said cavern comprising means forintroducing said liquids into said cavern, means for withdrawing,compressing, condensing and returning the vapors of said liquids to saidcavern, and an automatic control assembly means to actuate saidwithdrawal and compressor means, said automatic control assembly meansbeing responsive to an increase in the pressure above a firstpreselected pressure of said vapors.

8. In an underground storage system Lfor liquefied petroleum gas, incombination, an underground storage cavern, a shaft extending from thesurface of the earth to a region adjacent to said cavern, means forconnecting said shaft with said cavern, means for ascertaining the evelof the fluids in said cavern comprising a liquid level gauge assemblyincluding a float positioned within said shaft, and means for coolingsaid cavern to freeze the water in the earth surrounding said caverncomprising means for introducing said liquefied petroleum gas'into saidcavern, means for withdrawing, compressing, condensing and returning thevapors of said liquefied petroleum gas to said cavern.

9. In a system for the underground storage of liquids, in combination,an underground storage cavern in -a permeable, water-bearing formationbelow the minimum water table, a shaft connecting the surface of theearth to a region below and adjacent to said cavern, means forconnecting said shaft with said cavern, means for cooling said cavern tofreeze the water in the earth surrounding said cavern, said meanscomprising a compressor, amotor operatively connected to saidcompressor, a conduit having an inlet positioned above the level of`saidliquidsin said cavern and its outlet connected toV theinlet of saidcompressor, a condenser receiving the discharge of said 7 compressor, aconduit having one end thereof attachedtothe outlet of said condenserand having its other end positioned within said cavern which returnssaid compressed and condensed vapors to the region of the iloor of saidcavern, and means for the introduction and withdrawal of liquids to bestored in said cavern.

10. In a system for the underground storage of liquids according to'claim 9, a layer of ice covering the floor of said cavern, said conduitreturning the'compressed and condensed vapors to the region of the floorof said cavern having a substantial length thereof adjacent said otherend embedded in said layer of ice and in heat exchange relationshipthereto, the outlet of said conduit protruding upwardly above said layerof ice'.V

1l. In a system for the underground storage of liquids, in combination,a plurality of underground storage caverns in a permeable, water-bearingformation below the minimum water table, a shaft connecting the surfaceof the earth to a region below and adjacent to said caverns, means forconnecting said shaft with said caverns, means for cooling said cavernsto freeze the water in the earth t surrounding said caverns, said meanscomprising a compressor, a motor operatively connected to saidcompressor, a conduit having an inlet positioned above the level of saidliquids in said cavern and its outlet connected to the inlet ofrsaidcompressor, a condenser receiving the discharge of said compressor, aconduit having one end thereof attached to the outlet of said condenserand having its other end positioned within said cavern which returnssaid compressed and condensed vapors to the region of the floors of saidcaverns, and means for the introduction and withdrawal of liquids to bestored in said caverns.

12. In a system for the underground storage of liquids, in combination,an underground storage cavern in a permeable, water-bearing formation ofearth, a shaft exmotor to thereby withdraw the vapors of said liquids tocool said cavern to maintain the water in the earth surrounding saidcavern in a frozen condition which comprises a current source connectedto said motor, a switch to disengage said current source from saidmotor, a relay to actuate saidrswitch, and means to actuate said relayincluding a current source, a pressure responsive switch connected by aconduit means to the vapors in said cavern and temperature responsiveswitches positioned in the earth and water surrounding said cavern, saidpressure responsive switch and temperature responsive switches beingconnected in a parallel circuit with the coil of said relay and saidcurrent source, said pressure responsive switch opening at a rstpreselected pressure in said cavern and closing at a second higherpreselected pressure in said cavern, said temperature responsiveswitches opening at a rst preselected temperature in the earth and watersurrounding said cavern and closing at a second higher preselectedtemperature in said earth and water surrounding said cavern, means forcondensing the withdrawn vapors, and means for returning the condensedvapors to the lower region of said cavern.

13. An underground storage system according to claim ll wherein saidliquids stored therein are liquefied petroleum gases, wherein saidcavern is located below the minimum water table and at a depth below thesurface of the earth equal to approximately one foot of overburden foreach pound of pressure exhibited by said liquefied 8 petroleum gases ata temperature approximately equal to the freezing point of the water inthe earth surrounding said cavern.

14. In a system for the underground storage of liquefied petroleum gas,in combination, an underground storage cavern in a permeable,water-bearing formation, a shaft connecting the surface of the earth toa region adjacent to and below said cavern, a tunnel connecting saidshaft with the upper region of said cavern, a tunnel connecting saidshaft with the lower region of said cavern, afmetal liner in said shaftcemented in concrete in the earth surrounding said shaft extending fromthe shaft opening at the earths scrface t0 the top of the tunnelconnecting said shaft to the upper region of said cavern, a liquid levelgauge assembly including a iioat positioned within said liner in saidshaft to indicate the liquid level therein and thereby the 'liquid levelin said cavern, 'a metal Iliner head attached to said metal liner insaid shaft to seal said shaft atthe earths surface, a liquid withdrawalpipe means within said shaft and metal liner connecting the bottomregion of said shaft to the earths surface and a heated pump at thebottom end of said withdrawal pipe means, a liquid filler pipe meanswithin said shaft and metal liner, extending through said 'liner head tothe surface of the earth and connectingV the lower region of said cavernthrough said tunnel connecting said shaft with the lower region of saidshaft, vapor withdrawal pipe means within said shaft and metal linerextending from a region above the liquid level in said cavern throughsaid liner head to the surface of the earth, and compressor means andmotor therefor to withdraw vapors from said liquefied petroleum gas,said compressor means and motor therefor automatically being actuated towithdraw said vapors by an automatic control assembly comprisingtemperature responsive switches installed in the earth and watersurrounding said cavern and responsive to an increase in temperatureabove a first preselected temperature of the water in the earthsurrounding said cavern, and a pressure responsive switch connected by aconduit means to the vapors in said cavern responsive to an increase inthe pressure above a first preselected pressure of said vapors,condenser means to condense said withdrawn vapors and connected to saidliquid filler pipe means to return said condensed vapors to said cavern,and a layer of ice covering the oor of said cavern, said :liquid fillerpipe means returning the compressed and condensed vapors to the regionof the floor of said cavern having a substantial length thereof adjacentits outlet embedded in said layer of ice and in heat exchangerelationship thereto, said outlet protruding upwardly above said layerof ice.

15. An underground storage system for liquefied petroleum gas accordingto claim 14 wherein said cavern is located below the minimum water tableand at a depth below the earths surface equal to about one foot ofcverburden for each pound of vapor pressure exhibited by said liquefiedpetroleum gas where the maximum temperature of said liquefied petroleumgas is below the freezing point of the water in the earth surroundingsaidV cavern.

16. A method for sealing an underground cavern for the storage of liquidwhose freezing point is below the freezing point of water measured understandard conditions, said cavern having been formed in a permeablewater-bearing formation underground, which comprises introducing saidliquid into said cavern, vaporizing a portion of said liquid in directcontact with the `geologic formation and thus freezing water heldtherein, withdrawing the vapors of said liquid from said cavern,compressing and condensing said vapors, and returning said cornpressedand condensed vapors to sai-d cavern.

17 A method according to claim 16 wherein a plurality of undergroundcaverns are sealed.

18. An underground storage system for liquefied petroleum gas accordingto claim 14 in which the heated pump and withdrawal pipe means can beraised and lowered as a unit, said pump being adapted for `use in itslower 9 position for the removal of water and in its raised position forwithdrawing product from the underground storage system.

19. The apparatus of claim 18 in which the Withdrawal pipe means isprovided with a seal to prevent loss of stored fluids during raising andlowering of said pipe means, said seal being positioned at the upper endof said shaft.

20. The apparatus of claim 18 in which the heated pump is disposed in awell below the water level in the storage system and is provided withsuitable heating means whereby said pump can be released and raised fromthe Well when the storage system becomes frozen.

References Cited in the iile of this patent UNITED STATES PATENTSSooysmith Oct. 14, 1902 Sooysmth Nov. 11, 1902 Vedder June 8, 1920 BowieMar. 12, 1940 Kerr Jan. 18, 1949 Thompson May 1, 1951 Daxelhofer July14, 1953 Phelps Nov. 17, 1953 FOREIGN PATENTS Germany June 17, 1920

